Investigators at the University of California, Santa Barbara, led by material scientists Kristin A. Denault and Michael Cantore, have created high-power white light using a laser diode in combination with inorganic phosphors — an excitation source different from the traditional LEDs.

Bright white light (right) achieved using lasers in combination with phosphors next to an image of the phosphor with no illumination. Courtesy of K. Denault/UCSB.
LEDs can experience droop, a problem in which the LEDs’ efficiency falls as operating currents rise, making the lights too hot to power in large-scale applications.

“We found two ways to create high-intensity ‘cool’ white light,” Denault said. The first used a blue laser diode and yellow-emitting phosphor powder with a luminous flux of 252 lumens, which is comparable to current high-brightness white LEDs. The second method used a near-UV laser diode and a combination of red-, green- and blue-emitting phosphors.

The researchers also achieved a variety of other color temperatures with high color rendition, broadening the range of applications for these new lights, she said.